No it isn't N deficiency.
It could be a couple things but you have no pics so hard to pin down.
A micronute def can give you those talons but there are other things to check too.
-Potbound plants cup over like you are describing
-Nitrogen OVERDOSE in some cases can contribute to that.
FYI N deficiency is easy to spot as very pale and yellowing lower leaves.
stinkyattic Reviewed by stinkyattic on . curling leaves I have 2 plants growing in soil under CFL's some of the older leaves on the outside edges are starting to fold under and the tips are folding down to where they look like talons does anyone know what could be causing this? Rating: 5